Core drilling apparatus



Patented July 4, 1939 UNITED STATES PATENT OFFICE CORE DRILLING APPARATUS tion of Texas Application January 8,

Claims.

This invention relates to core drilling apparatus, and more particularly to a novel combination of a drill stem, core drill, core barrel, and valve for use in connection therewith.

1 It is a general object of this invention to provide a core drilling apparatus which will not become clogged with debris while being lowered into a hole.

Another general object of the invention is to m provide a core drilling apparatus which can be "floated into a hole containing drilling mud or other liquid.

In the construction of core drilling apparatus it is customary to mount on the lower end of a drill stem a bit capable of cutting an annular hole and having therewithin a core barrel capable of receiving the core formed when such annular hole is cut. The upper end of the core barrel is ordinarily provided with an opening through which the liquid within the core barrel can escape as the drill passes down over the core. This opening has in the past been provided with a check valve permitting upward but preventing downward flow so that during the operation of coring, drilling fluid can be pumped downwardly through the drill stem and through passageways provided for the purpose outside of the core barrel without this fluid being pumped into the core barrel against the top of the core.

It has been found, however, that with the construction just described when the same is being lowered into a well containing drilling fluid having therein cuttings and other miscellaneous solid material, the drilling fluid and this solid material will flow in through the bottom of the core bit, up through the core barrel and into the drill stem where the solid materials will settle with the result that when drilling is started the drill stem may be choked to such an extent that circulation will be prevented and the core barrel may be contaminated with this foreign material to such an extent that the core subsequently taken will be contaminated and not truly representative of the formation from which it is taken.

It is also desirable in lowering a tool of any type into a well on the lower end of a string of pipe to be able to partially or wholly prevent the influx of liquid to the pipe so that the buoyant efiect of the liquid on an empty or partly empty pipe will serve to partially sustain ,the weight of the pipe and tool on the lower end thereof during the time that it is being lowered into the well.

In view of the foregoing, it is an object of this 55 invention to provide a device of the type set 1938, Serial No. 183,977

forth which will prevent the accumulation oi foreign solid material within the core barrel or the drill stem during the lowering of the same into a well.

Another object is to provide such a device which will also prevent the influx of a substantial amount of liquid into the drill stem during the lowering of the device into a well, thereby permitting the device to be floated into the well.

Another object of this invention is to provide such a device which does not require the dropping of any weights or actuating members into the drill stem after the same has been lowered into a well.

Another object of this invention is to provide a device which will be automatic in its operation, and which will not require the exercise of any unusual skill on the part of the operators.

Another object of this invention is to provide a single valve which may serve both as a float valve for floating the apparatus into a well, as a valve for preventing the accumulation of solid materials in the core barrel and in the drill stem. and which will serve to prevent down-flow through the core barrel during the core drilling operation.

Other objects and advantages of this invention will become apparent from the following description and the accompanying drawing in which is set forth by way of illustration one embodiment of this invention.

In the drawing:

Fig. l is a vertical cross sectional view of a device constructed in accordance with this invention as it is being lowered into a well hole having drilling fluid therein.

Fig. 2 is a view similar to Fig. 1 but showing the device during the core drilling operation.

Fig. 3 is a similar view showing a continuation of the upper portion of Fig. 2.

Referring now more particularly to the drawing, the drilling apparatus illustrated is lowered into a well hole I on the lower end of a drill stem 2. At the lower end of this drill stem there is provided a special section 3 externally threaded at its lower end to receive the coupling ,4. To the lower end of this coupling is secured the outer barrel 5 upon the lower end of which is threaded the fitting 6 which in turn carries the core bit I. Mounted within the outer barrel 5, the fitting 6 and the core bit I, is the inner core barrel a spaced from the outer barrel at its lower end by ribs 9. This barrel at its lower end is provided with an enlarged portion i0 seating onthe shoulder Ii within the core bit and receiving the upper sleeve-like part l2 of a core catcher sleeve 13 which is likewise seated within the core bit. The core catcher sleeve is notched as at l4 and i5 for the purpose of receiving the core catcher blades l6 and II, respectively, which are pivotally mounted therein. These blades are retained in position by the retainer sleeve l8.

It is to be noted that the opening through the inner barrel is substantially the same size as the opening through the bit head 1, and that the bit head I is provided at its lower end with roller cutters l9 and 20 adapted to cut an annular hole leaving a central core to rise through the opening in the bit head I and into the inner core barrel 8.

At its upper end, the inner core barrel 8 is provided with a head 2| having external ribs 22 thereon for the purpose of spacing the inner core barrel from the outer barrel adjacent its upper end. This head 2| has a passageway 23 upwardly therethrough internally threaded at its upper end at 24 for a purpose presently to be set forth. At its upper end also the head 2| is provided with a countersunk portion adapted to receive a valve seat member 25 presenting an upwardly facing valve seat 26 and held in place by the lower end of a cage member 21 which is threadedly mounted within the countersunk portion of the head 2|. This cage 21 is formed with lateral openings 28 therethrough and has its upper end projecting upwardly into a countersunk portion 29 within the lower end of the special section 3. A rubber bearing ring 38 or other means for forming a combined thrust bearing and seal is interposed between this upwardly extending part of the cage member for the purpose of taking the end thrust on the core barrel 8 during the cutting of a core and forming a liquid tight seal between the upper part of the cage member and the special section 3 during the lowering of the device into a well.

Threaded into the upper end of the cage member 21 is a second valve seat element 31 having a downwardly facing valve seat 32. Between these two valve seats is interposed a valve which in the present instance is shown in the form of a ball 33. The cage member 21 is preferably of substantially uniform internal diameter throughout its length, and is of a diameter such as to permit the valve 33 to move freely upwardly and downwardly, but to prevent substantial lateral movement of the valve at any point.

In operation, the device is assembled as shown in Fig. 1, and is lowered into the well. As the lowering operation is begun the dropping of the tool and the first sections of drill pipe through the liquid standing within the well causes this liquid to at first rush upwardly through the inner core barrel 8, through the passageway 23 and into the drill stem. However, this rush of liquid very quickly carries the valve 33 upwardly into seating engagement with its upper seat 32, and thereafter no fluid can flow upwardly into the drill stem. Since fluid is not permitted to flow upwardly into the drill stem, the fluid within the core barrel 8 will be substantially static and there will be no flow upwardly into or through the core barrel. The slight flow which takes place during the closing of the valve 33 against its upper seat is so small that no substantial settling or clogging can result from the small amount of solid material which it might contain, and inasmuch as no further flow is permitted either through the core barrel or into the drill stem, the device can be lowered to the bottom of the hole Without substantial accumulation of foreign material therein.

During this lowering operation also, since liquid is not permitted to enter the lower end of the drill stem, the drill stem will remain empty and will be subjected to the buoyant effect of the liquid in the hole outside the drill stem so that a portion of the weight of the drill stem and the apparatus attached thereto will be buoyed up by the liquid.

When the device has reached the bottom of the Well and it is desired to begin the drilling operations, drilling fluid which does not contain the objectionable solid material referred to is poured into the upper end of the drill stem filling it until the head of liquid outside of the drill stem which during this time is acting on the lower face of the valve 33 to hold it seated is substantially balahead by the head of liquid within the drill stem. When this occurs the valve 33 will drop of its own weight until it is in contact with its lower seat 26. At this time, circulation may be started, the drilling fluid being pumped downwardly through the drill stem, out through the lateral openings 28 in the cage 21, down between the ribs 22 and 9 and about the outside of the inner barrel 8, and out through passageways provided therefor in the bit head I. This drilling fluid cannot enter the upper end of the inner barrel 8 because of the fact that the valve 33 is now seated upon its lower seat 26. Drilling is then begun and as the drilling proceeds the core which has been designated by the numeral 34 in Fig. 2 will rise into the inner barrel 8. As this occurs, the liquid within the inner barrel 8 will be gradually forced upwardly through the passageway 23 and out past the valve 33 which now acts as a check valve to prevent downward flow into the core barrel 8 while permitting upward flow out of the same. After the core has been taken, an upward pull on the drill stem causes the core catcher blades H to move downwardly and inwardly toward the position shown in Fig. 1, thus gripping the core 34 and causing it to break off and be retained in the inner barrel 8. The apparatus is then withdrawn from the well, and it is noted that during this withdrawal fluid may drain out of the drill stem through the lateral openings 28 and through the various passageways through which it was pumped during the drilling operation. When the apparatus has been removed from the well, the member 3 may be disconnected from the member 4 and the cage 28 removed from the head 2 I, thus permitting removal of the valve seat member 25. The bit head 1 will also be removed from the fitting 6, permitting the removal of the core catcher and exposing the lower end of the core and the inner barrel 8. A pipe may then be threaded into the threaded opening 24 and pressure applied to this opening to force the core from the inner core barrel 8 out through the lower end thereof for examination purposes.

It will be seen from the foregoing that a device has been provided whereby it is possible to float a core drilling apparatus into a well, to dislodge the means which permitted this floating action without necessity for dropping weights into the drill stem or for pumping against the same, and to cause this same means to act as a check valve for the core barrel during the coring operation.

It will further be seen that by the arrangement set forth there has been provided a means for preventing the influx to the core barrel and drill stem of contaminated drilling fluid, and for preventing the accumulation therein of solid materials contained in such drilling fluid.

It will be seen further that the apparatus described is simple in construction and operation, and that it accomplishes all of the objects sought by this invention.

Having described my invention, I claim:

1. In combination, a drill stem, a core drill on the lower end thereof, a core barrel extending upwardly from said core drill within said drill stem and having an opening at its upper end, said drill stem having slush passages th rein outside of said core barrel, a downwardly facing valve seat within said drill stem above said core barrel, an upwardly facing valve seat within the opening at the upper end of said core barrel, a cage extending between said valve seats and a valve movable within said cage to seat against either of said valve seats.

2. In combination, a drill stem, a core drill on the lower end thereof, a core barrel extending upwardly from said core drill within said drill stem and having an opening at its upper end, said drill stem having slush passages therein outside of said core barrel, an upwardly facing valve seat within the opening at the upper end of said core barrel, a substantially cylindrical cage projecting upwardly from said valve seat into the drill stern and having a part fitting snugly within said drill stem, a downwardly facing valve seat carried on the upper end of said cage, and a valve movable within said cage to seat against either of said valve seats.

3. In combination, a drill stem, a core drill on the lower end thereof, a core barrel extending upwardly from said core drill within said drill stem and having an opening at its upper end, said drill stem having slush passages therein outside of said core barrel, a downwardly facing valve seat within said drill stem above said core barrel, an upwardly facing valve seat within the opening at the upper end of said core barrel, a cage extending between said valve seats, a valve movable within said cage to seat against either of said valve seats, and means forming a seal between said drill stem and the upper end of said cage.

4. In combination, a drill stem, a core drill on the lower end thereof, a core barrel extending upwardly from said core drill within said drill stem and having an opening at its upper end, said drill stem having slush passages therein outside of said core barrel, a downwardly facing valve seat within said drill stem above said core barrel, an upwardly facing valve seat within the opening at the upper end of said core barrel, a cage extending between said valve seats, a valve movable within said cage to seat against either of said valve seats, and means rotatably supporting said core barrel against upward movement within said drill stem and forming a seal between said drill stem and the upper end of said cage.

5. In combination, a drill stem, a core drill on the lower end thereof, a core barrel extending upwardly from said core drill within said drill stem and having an opening at its upper end, said drill stem having slush passages therein outside of said core barrel, a downwardly facing valve seat within said drill stem above said core barrel, an upwardly facing valve seat within the opening at the upper end of said core barrel, a cage extending between a part on said core barrel and a part on said drill stem, a valve movable within said cage to seat against either of said valve seats, and a rotatable bearing and sealing means between one end of said cage and one of said parts.

JOHN E. HOFFOSS. 

